The overall goals of the Mayo Clinic Urology O'Brien Research Center are to develop new diagnostic strategies in order to accurately phenotype patients and thus apply improved individualized management strategies. We will pursue these goals via 4 interlinked multidisciplinary projects. Important and timely aims of the Mayo Clinic O'Brien Urology Research Center include: 1) Develop and validate a comprehensive low-dose stone-characterization exam using clinical dual-energy CT techniques in order to predict stone fragility, and to develop new CT methods capable of detecting the earliest possible precursor lesions. 2) Determine factors that produce NL precursor lesions including Randall's plaques and tubular plugs. 3) Define specific factors that increase the risk of kidney stones and their recurrence, and develop clinical prediction tools to help clinicians identify high-risk patients.